1. Field of the Invention
The present invention generally pertains to methods of treating odors, particularly odors and present within enclosed environments, using nanocrystalline metal oxide and metal hydroxide particles.
2. Description of the Prior Art
Common sources of malodors include smoke/tobacco, human and pet excrements, mold and mildew, bacteria, food, beverages (spoiled milk), vomit, and dirty clothes. Although malodors have a multitude of different sources, chemically speaking, most malodors are organic (carbon containing compounds) in nature. Malodors, can easily permeate, penetrate, impregnate and cling to organic surfaces within enclosed environments such as cars and buildings.
Various types of odor problems occur in homes. Some of the leading causes of nuisance odors are the result of the biological contamination. When these microbial organisms decay and rot, they give off gases and noxious fumes. Unfortunately these are not just aesthetic problems. Health concerns ranging from nausea to death can arise from acute and repeated exposure to these and other odor causing compounds. Indoor air pollution is now considered by the EPA and Congress to be America's No. 1 environmental health problem. It is estimated that 4-5 million Americans already suffer from the effects of chemically induced environmental illnesses. Tightly sealed buildings and homes may be more energy efficient but can trap pollutants and microbes indoors causing allergies, odors, mold, and illness.
Furthermore, the EPA conducted a 17-year study and found that women working in their homes had a 55% greater risk of dying from cancer than those who worked in an office, primarily due to the use of ordinary household cleaners. Some of the products found in American homes have chemical ingredients that are potentially harmful. These products include oven cleaners, paint removers, pesticides, solvents, drain cleaners, and more.
Treatment of malodors is generally approached in two ways: masking or elimination. If odor masking is used, the source of the mal odor is not eliminated and will eventually return once the “masking” agent is removed. In many cases, the malodor is so overpowering that a masking agent is ineffective. Treatment by elimination, on the other hand, removes the malodor by removing its source. Elimination can be done by physically replacing the contaminated surface or by removing the malodor-causing agent itself.
Numerous compositions and methods have been developed for reducing odors from a variety of sources; however, they have had only limited success because the odors associated with a wide range of sources are complex and can comprise a mixture of different substances including, but not limited to inorganic bases such as ammonia, organic acids such as butylic acid and isovaleric acid, and neutral molecules such as acetaldehyde and methyl mercaptan. The most common ways of reducing malodors caused by these substances include: (I) masking the odor using an odor-masking aroma, (ii) adsorption of the odor using inorganic materials, such as activated carbon, sodium bicarbonate, and talcum powder, and (iii) using a composite, such as chlorine dioxide, for reducing bacteria which produce the malodorous substances. However, these methods present the following problems: (I) the odor is not eliminated, but only masked, (ii) the adsorption capability of these traditional sorbents is limited, (iii) by using the oxidizing agent, a secondary pollutant can be produced, and (iv) the sorbents can be effective only under certain conditions such as a wet environment.